Keith if you e mail me..... antonbird@talktalk.net I can send some pictures plus a sketch of measurements. I worked in Alloy wheel business, Design, production & development for 15 years, Remember "Cosmic" 12 years with them then I became the technical manager of Cobra.
These wheels have 1/4 " inset (which some people confuse for off set - they are different).
They went straight on the back of my MK 1 with only a tiny nip out of the arch & on front I used 1/8" spacer to clear bottom joint.
Regds